The key to an executive’s success often lies with the strength of their professional network. This is a collection of the best relationships you have developed over years of business experience and can come in handy if you’re looking for a new job, a new client, or even just an introduction.

But if you haven’t talked to someone in years, that kind of request isn’t likely to go over well. Relationships lose their value when neglected, and then you’re left without a network.

We’ve got some tips for how to preserve business relationships and connections for years of networking.

Keep a record

Social media has made keeping track of contacts a bit easier with LinkedIn and other professional networking sites, but even these aren’t fail-proof, as not everyone updates their profiles regularly. We recommend keeping a spreadsheet of your contacts. Include their names and contact info at the very least, but feel free to include more. If your professional network is a large one, include a note on how you know them. Record the date of the last time you talked and notes about that conversation to have something to refer back to in your future interactions with them. Update the spreadsheet each time you talk to or email a contact to keep it relevant.

Reach out

Once every month or two, send your contacts an email. Ask how they’re doing and what you can do for them. Most often there won’t be anything you can do to help, but your connections will know that you care about them and the success of their career. They’ll be more likely to come to you for help if something does come up, but they’ll also be more likely to return the favor if you ever find yourself needing professional assistance.

But don’t limit your contact to monthly or bi-monthly emails. Introduce contacts from different circles who you think would benefit each other. If you help someone in a way that a contact previously helped you, share the experience with them and thank them for their help. If you read an article or essay that makes you think of one of your contacts, send it to them with a quick note explaining why it reminded you of them. Better yet, mail them a physical copy and handwritten note. The key to staying connected is just that — staying connected.

Respond quickly

Professionals who do the kind of regular checkups with their connections like we talked about above usually have a fairly good response rate. But it’s not enough to just reach out. When your contacts respond, so should you, and quickly. If your contacts had questions or requests, answer them. But even if they didn’t, still send back a quick note in response. This shows you care about them beyond just the obligatory hi-how-are-yous, and is one of the most forgotten elements to building relationships.